Process of reducing ores



Patented Dec. 30, 1930 I UNITED STATES PATENT OFFICE HERBERT WITTEK, F BEUTHEN, GERMANY PROCESS OF REDUCING ORES No Drawing. Application filed December 1, 1926, Serial No. 152,069, and in Germany July 26, 1926.

During the azotizing of carbides considerand obtained in a condensing plant. If sulable quantities of heat are liberated which phurous ores are used carbonic disulphide is have, hitherto, been utilized only partly, for produced in the oven which can be isolated instance, for heating to the reaction temperfrom the gases of reaction in the well known ature other masses of carbide yet to be nitrogmanner.

enized. At the nitration of calcium carbide The nitro-lime which is obtained by the nifor instance, the exothermal heat generated tration of 'alcilun-carbide by nitrogen or usually causes super-heating, and consequentammonia according to the present process is ly decomposition of the nitro-lime which is superior to the nitro-lime obtained by the 10 formed, and thus prevents complete utilizahitherto applied process, for the reason that tion of the carbide. During the nitration as it is practically free of carbide. The nitrowell as at the preliminary heating of the carlime is delivered from the oven not in. the bide, carbon andhydrogen and other reducform of a solid block, but in the form of a ing gases are liberated which get lost without loose mass. as fusion of the mass does not 15 being utilized. take place owing to the suppression of the It has been ascertained by experiments that super-heating. It is consequently not necesthe heat liberated atthe azotizing of carbide, sary to pulverize the mass to the usual state as well as carbide which remains non-ut li ed of dust for producing an effective fertilizer. at the usual azotizing, and also the above It is also possible to proceed in suchaman- 20 mentioned liberated iubstances may be adner that the carbide admixed with ore or cov- 7 XHIItHQQOlISly utilized for the reduction of ered by ore is first brought to reducing reacores, if the reduction is made to take place in tion temperature in a stream of nitrogen by combination with the azotizing of carbides. direct heating of the carbide, with the conse- Evidently only such compounds can be utilquent production of reducing gases, After ized during the nitration which do not prethe reduction, the nitrogen then begins to vent nitrogen binding with the carbide. act upon the carbide in the heated state.

' ()res the metals of which separate by dis- The advantage is thus obtained that the gases tillation at the temperatures in question are capable of reaction with the ore, generated at specially adapted for the p o e s- The p o the heating of the carbide, which are other- 30 ess is very advantageous for the production wise lost, are utilized for the reduction of of nitro-lime from calcium carbide. The or s,-

ore's admixed with Carbide, lt rn ing The reduction of the ores could also be carlayers of ore and carbide can be reduced in ri d out in a special oven, only th quantity the oven at the same time that the nitration is of h at hi h i lib t d t th ti i taking place. In this manner the li ilgle of carbide being used for heating and reduo able effects of super-heating are avoided ing the ores, or the reduction of the orcs may which otherwise occur during nitration by becarried out in a special oven. the gases known methods, whereas in the present procliberated at the heating: of the carbide and at ess the liberated heat is utilized at once for the azotizing beimg used as reduction means. the reduction of the ores. The liberated car- If the object is to obtain only at ca rbide-free bon and gases exert further a strong reducnitro-lime the reduction of the ores can be ing efi'ect which is further favored by the utilized to produce from raw intro-lime a carbide remainder the azotizing of which has, carbide-free calcium nitrogen, by bringing to I up to the present, been very difiicult. reaction with the ores to be reduced the For. this process zinc ores, for instance calapulverized raw nitro-lime which still contains mine, are specially adapted; When a mixfree Carbide.

ture of calamine and carbide is used, the re- Instead of carbide. mixtures of carbide duction of the zinc ore takes place in the forming elements might evidently be used for oven together with the formation of nitrothe azotizing process without altering the lime, the zinc being separated by distillation process. To the carbide, as well as to the mixtures of carbide forming elements, thelmown additions, as calcium chloride, calcium fluoride, sodium chloride or the like, may be added which reduce the reaction temperature or accelerate the reduction.

Instead of calcium carbide, other carbides may be used for the reduction of the ores, for instance barium carbide. In this case barium cyanide is almost exclusively obtained. If strontium carbide is used, mixtures of the cyanide and of the cyanamide are obtained. When cyanides are formed the portion of the carbon of the carbide used for the binding of the cyanide is not at disposal for the reduction.

The quantity of carbide consumed in the reduction process can be reduced by adding at the same time coke to the carbide. The coke is either mixed with the carbide or placed in layers upon the carbide. Semi-coke is specially adapted as an addition, as it generates, prior to and at the occuring reduction temperatures of 800 to 1l00 0., considerable quantities of hydrogen, the good effect of which at the reduction is generally known. By the addition of semi-coke the consumption of carbide for the reduction process is reduced and the lucrativeness of the process increased.

The invention has numerous applications, some examplesof which are as follows:

A mixture of 170 parts by weight of carbide with 12 parts by weight of pyrite is heated in nitrogen gas to 1100 C. and nitrated as usual. The residue contains a calcium cyanamide of about 20% nitrogen and also the iron-in finely divided metallic form. After comminution of the reaction product, the iron may be separated from the calcium cyanamide by washing, or by means of an electromagnet.

A mixture of 170 parts by weight of calcium carbide with 13.5 parts by weight of roasted blende is heated to 1000-1100 C. and treated with nitrogen. As soon as the nitration is completed and While nitrogen is passed through the same, the mass is allowed to cool. A calcium cyanamide of 20% nitrogen is obtained; it contains only a trace of zinc dust. In'the receiver from 80 to 9.0% of the zinc is held in solid form. The rest is obtained from the waste gases by a dust removing device.

The carbide exposed to nitration is covered with a layer consisting of 100 parts of cinnabar and 100 parts of coke. By direct heating the carbide is first brought to the reaction temperature 'in the stream of nitrogen.

in consequence of the vapor stream, the mercury is driven out of the ore coke mixture, practically without residue. The volatile mercury is obtained as usual by a condensation pipe system, cooled by air and water, partly as a fluid mass and partly as the socalled mercurial soot.

I claim 5- 1. The method of reducing ores which consists in contacting the ore and carbide, and then az otizing the carbide, while the ore and carbide are thus associated.

2. The method of reducing ores which consists in mixing the ore and carbide, and-then azotizing the carbide.

3. The method of reducin ores which consists in mixing the ore, a car ide and a semicoke, and then azotizing the carbide.

4. The method of reducing ores which consists in passing a stream of nitrogen through a mass composed of alternating layers of ore and a carbide, heating the mass, whereby nitration of the carbide is effected, and recovering the metal of the ore liberated by the products of nitration.

5. The method of reducing ores which consists in azotizing a mass composed of the ore and calcium carbide, whereby a nitro-lime is formed and heat evolved, and separating the pietal from the ore by means of the evolved ieat.

6. The method of reducing ores which consists in forming a mixture of the ore and carbide containing compounds, and then azotizin the carbide.

T. The method of reducing ores which consists in forming a mixture of the ore and carbide forming elements, heating the mixture to form carbides, azotizing the carbides, and reducing the ore by means of the evolved gases.

8. The method of reducing ores which comprises forming a mixture of ore and nitrolime containing carbide compounds, then reducing the ore by the carbide, whereby a pure nitro-lime is obtained and the ore is reduced.

In testimony whereof I aflix my si nature.

HERBERT WITT EK. 

